Lubricating oils



Patented Mar. 10, 1936 UNITED STATES PATENT OFFICE LUBRICATING OILS tionof Illinois No Drawing. Application July 1, 1935, Serial No. 29,423

17 Claims.

This invention relates to lubricating oils and it comprises an improvedlubricating oil to which has been added a small amount, of the order of0.1 to 1 percent, of the Friedel-Crafts reaction 5 product from a higherfatty. acid chloride and a coal tar fraction.

Within recent years efiorts have been made to improve minerallubricating oils by adding various ingredients thereto. In many casessuch additions have been made for the purpose of improving thatcharacteristic of the oil commonly referred to as oiliness. These addedsubstances have mostly been fatty acids such as oleic acid, variousglycerides, lard, and the like. The prop- 15- erty of oiliness has notbeen clearly defined, but

the term has a rather definite meaning to those skilled in the art. Somehave defined it as that property which an oil must possess to asufficient degree to enable the oil to lubricate adequately under allconditions of use. In more practical terms, on oily oil is one whichwill form a film between bearing surfaces of such strength that the filmwill withstand rupture under extreme conditions of pressure ortemperature. To put it another way, an oily oil is one which has highfilm strength and as a result will give better engine performance underall conditions of use. At the same time, however, such oilsshould havelow internal friction and should also have the 30 property of clingingto metal surfaces. It used to be considered that viscosity was a goodcriterion of the oiliness in oil on the theory that the higher theviscosity the stronger would be the M oil film. However, it has now beenpretty well acknowledged that viscosity alone does not explain oilinessin an oil.

As stated, the prior art has hitherto added small quantities ofvegetable oils such as oleic acid to hydrocarbon lubricating oils.Undoubtedly such additions have proved beneficial, in part because ofthe high polar characteristics of the higher fatty acids. That is to saythe carthem. This is because of the internal friction in the oil itself.4

Another serious objection to the addition of substances like oleic acidand fats is that these creased power losses in engines lubricated with.

added substances do nothave very much resistance to-high temperatures.In a gasoline engine the crank-case temperature may on the average beabout 210 F. and bearing temperatures may run as high as 400 F. Bearingpressures may occasionally be as high as 600 pounds per square inchwhich means that a satisfactory oil must have high film strength andheatresistance if it is to function continuously under these conditions.

Substances like oleic acid are not sufficiently heat resistant tooperate satisfactorily over long periods of time at the relatively hightemperatures in a rapidly rotating bearing. These substances, althoughthey initially contribute oiliness to an oil, tend to break down anddecompose at high temperatures. izing, or it may in part be institutedby the presence of traces of moisture. Fatty esters are readilyhydrolyzed at the high operating temperatures in the presence ofmoisture and free fatty acids thus liberated tend to decompose. All ofwhich means that such substances, although they may initially improve amineral lubricant very soon lose their eflectiveness and actually provedetrimental.

We have now discovered a class of materials which can be added tomineral lubricating oils in small amounts, ofthe order of 0.1 to 1percent, and which markedly improve the oiliness of the oil, but do nothave the many disadvantages unavoidably present in substances hithertosuggested. We have further discovered that the. compounds we add tolubricating oil markedly reduce the pour point of the oil. In someinstances we have been able to reduce the pour point of. the originaloil as much as 60 F. This is a phenomenal pour point lowering and hasnever hitherto been achieved so far as we are aware by the addition of aso-called pour point depressor. Moreover, many of the compounds we addincrease the viscosity index of the oil, which is highly desirable.

The class of substances coming within the scope of our invention can bebroadly defined as the Friedel-Crafts reaction product fromavhigherfatty acid chloride and a coal tar fraction.

. tained by reacting a higher fatty acid chloride with a coal tarfraction, distillate, acid-soluble or This action may be oxidchemicalindividuals. Our compounds may con- .tain complex ketonic substances,condensed aromatic hydrocarbons of high molecular weight, and possiblymany other kinds of organic substances. For this reason we cannotspecify our compounds by name but must refer to them by the process bywhich they are made. We know of no other way of defining themaccurately.

We shall now describe many different specific addition agents fallingwithin the generic scopeof our invention. It is to be understood ofcourse in each instance from about 0.1 to lper cent of these substances,or mixtures thereof, are dissolved in the mineral lubricating oils.

As stated, our addition agents are obtained by reacting a higher fattyacid chloride with a coal tar fraction in the presence of aluminumchloride. Many different higher fatty acid chlorides can be used asstarting materials, and by higher fatty acid chlorides we mean toinclude all those higher fatty acid chlorides derived from fatty acidscontaining six or more carbon atoms. The higher fatty acid chlorides aremade by reacting the corresponding fatty acid with phosphoruspentachloride or other chlorinating agent customarily employed forconverting fatty acids to corresponding acid chlorides. All of theseacid chlorides have the formula RCOCl. Acetyl chloride is the lowestmember of the series but we do not prepare our addition agents from thismaterial. We only use acid chlorides derived from fatty acids containingat least six carbon atoms. By definition higher fatty acid means analiphatic carboxylic acid containing at least six carbon atoms. In thepractice of our invention we can make addition agents from caproylchloride, capryl chloride, lauryl chloride, myristyl chloride,

' palmityl chloride, stearyl chloride, and also the acid chloridescorresponding to arachidic, behenic, carnaubic, cerotic and melissicacids. We can also use higher fatty acid chlorides derived fromunsaturated fatty acids such as oleic and linoleic. In most instances weuse mixtures of various fatty acids since these are readily obtainablefrom glycerides occuring in nature.

Likewise in the practice of our invention we can make our additionagents from liquid and solid fractions of coal tar and we generally usethose fractions, or distillates, boiling from 200 C. upward. Thefractions, distillates, or extracts which we use are generally mixturesof various aromatic and heterocyclic hdyrocarbons, phenols, cresols andother substances of complex structure. One of the most desirablematerials for addition to lubricating oils is that made from reacting ahigher fatty acid chloride with a coal tar distillate known as red wax.Red wax is a coal tar fraction having a boiling range of about 432 C. to500 0. Many of the coal tar distillates which we use in our inventioncontain quantities of naphthalene and anthracene admixed with otherhydrocarbons, phenols, creosols, and the like and our invention dealsparticularly with addition agents made from these mixtures and not withpure constituents thereof. As stated above many of the desirablecharacteristics in the products which we add to lubricating oils are dueto the fact that these products are mixtures of substances and are notpure chemical compounds.

We shall now describe our invention with specific reference to preparingproducts from many different coal tar fractions, and the additionthereof to lubricating oils. In order to keep our disclosure within.reasonable bounds we shall rcstrict our specific examples to additionagents made from stearyl chloride. This acid chloride can be made fromstearic acid readily. It is to be understood, however, that all of thehigher fatty acid chlorides enumerated above can be used instead ofstearyl chloride.

We shall now refer to products obtained by reacting so-called crudetower bottoms with stearyl chloride. These crude tower bottoms have aboiling point range of about 230 C. to 375 C. They are obtained bydistilling coal tar and condensing a fraction having this boiling pointrange. The exact composition of the crude tower bottoms is not known butthey contain anthracene, naphthalene, and probably many othersubstances.

We first prepare a mixture of about 35 parts by weight of the towerbottoms, 73 parts by weight of stearyl chloride, and 258 parts by weightof carbon disulphide. To this mixture we add, at room temperature, 67parts by weight of aluminum chloride over a period of three hours. Themixture is then refluxed for about two hours at 46 C. and then pouredupon a mixture of ice and hydrochloric acid. The mixture is thensteamdistilled, this resulting in the hydrolysis of a complex aluminumcompound probably analogous to the usual type of compound obtained inthe Friedel-Crafts synthesis. When the hydrolysis is complete theproduct obtained will appear as a reddish-brown, free-flowing oilfloating on the surface of the aqueous mixture of aluminum chloride.Hydrolysis should be continued until this oily reaction product issubstantially free of aluminum.

The chemical composition of this reaction product is not clearlyunderstood. It probably contains ketonic compounds derived from anthracene and stearyl chloride. But since phenols and creosols are alsopresent in the initial coal tar fraction it is apparent that the finalreaction products are probably quite complex.

We now add from 0.1 to 1 per cent of this reaction product to alubricating oil to be improved.

When added to an SAE number 30 mid-continent lubricating oil the pourpoint of the oil is reduced from 20 F. to 15 F. the oiliness of the oilis markedly increased We can vary the ratio of coal tar fractionstarting material to stearyl chloride over rather wide limits. Insteadof starting with these crude tower bottoms we can start with variousfractions thereof. For example, 35 parts by weight of the fractionboiling range 315 C. to 330 C., and '73 parts by weight of stearylchloride will give Friedel- Crafts reaction product which, when added toa lubricating oil, so that the 011 contains 0.5 percent thereof, willreduce the pour point from 20 F. to 5 F. That fraction of crude towerbottoms, boiling range 230 C. to 345 C., will give a pour point loweringin the same oil of 20 F.

We shall presently tabulate the results obtained from many other coaltar fractions, distillates and extracts. It is to be understood, ofcourse,

' that in each instance stearyl chloride is reacted with the coal tarfraction in the presence of a formity with the' usual practice in theFriedelsolvent such as carbon disulphide and an aluminum chloridecatalyst. In general the quantity .limits and should of course be enoughto insure solution of the reacting constituents. Any skilled chemistfamiliar with the Friedel-Crafts reaction will understand itsrequirements. In con- Crafts synthesis the first reaction product(complex aluminum compound), is hydrolyzed to remove aluminum and thefinal reaction product (viscous oil or waxy solid) is removed and thenadded to the lubricating oil.

The table which follows tabulates results obtained when 0.5 percent ofreaction product is added to a number 30 SAE Mid-Continent oil. The pourpoint of the original oil was 20 F. and the table gives the pour pointlowering observed. In each instance the addition compound was made from73 parts-of stearyl chloride, and except where otherwise noted, thequantityof coal tar fraction starting material was 35 parts by weight.For example, the table gives data for crude red wax in three differentquantities, one being35 parts by weight, another 70 parts and a third140 parts. Likewise the amount of aluminum chloride is constantthroughout and is about equal to the Weight of stearyl chloride.

Before tabulating the data we obtain, a description of the variouscoaltar fractions in" the table will be helpful. The crude tower bottomshave already been described above. The fractionated crude tower bottomsare distillation cuts made from tower bottoms and having the boilingpoint ranges (1.3. P. R.) indicated. The alkaliwashed tower bottoms arethe residue obtained after washing the tower bottoms with severalportions of 20 percent caustic soda solution until no further substancescan be extracted with alkali from the tower bottoms. The alkali washingsfrom crude tower bottoms are the alkali-soluble materials in thealkaline solution used for extraction. These were recovered byneutralizing the alkaline extraction liquors with an acid to liberatethe alkali-soluble constituents. The

neutralized solution is advantageously extracted with ether to removeany alkali-soluble constituents not thrown out on neutralization, theether is then evaporated, and the alkali-soluble constituents reactedwith stearyl chloride.

In a similar manner the tower bottoms were washed with 40 percentsulphuric acid solution to obtain the acid-washed tower bottoms, and theacid-soluble constituentswere recovered from the acid washings byneutralizing and ether extraction. The acidand alkali-washed towerbottoms are the residue of washing the tower bottoms with both acid andalkali.

Crude red wax is the product obtained when coal tar pitch is distilled.Crude red wax is that distillate having a boiling point range of about432 C. to 500 C. In a further example this material was also acid Washedand the product after acid extraction reacted with stearyl chloride asindicated in the table. The coal tar overheated distillate was afraction of the red wax with a boiling range of 450 C. to 500 C.

The light coal ,tar bases were obtained from commercial sources and aresubstances obtained from coal tar by extraction with sulphuric acid.These bases have a boiling point range of from about 100 C. to 355 C.,80 percent of which boils substantially over200 C. The heavy coal tarbases are products similarlyobtained from coal tar by extraction withvsulphuric acid and over 95 percent has a boiling point range of 239C.'to 391 C.

The crude anthracene was a coal tar distillate containing approximately40 .percent anthracene, the remainder being naphthalene, methylnaphthalene, carbazol, fiuorene, phenanthrene and othersubstances. Thecrude anthracene product purified" was also crude anthracene-stearylchloride reaction product which was fractionated by distillation inorderto remove unreacted anthracene and naphthalene. Approximately 10percent of the crude material was distilled off, the remainder beingused for addition to the oil. The acid-washed crude anthracene was, asits name implies, the residue from washing crude anthracene withsulphuric acid and then reacting with stearyl chloride.

Three other coal tar distillates are described, these being three cutsfrom material boiling from 300 C. to 500 C. The creosote oil residuesare material commercially obtainable by that name on the market and weremade by extracting coal tar with an alkali, neutralization of theextract and isolation of the creosote therein.

Although we specifically mention creosote oil residue from coal tar wecan use such residues from wood tar and petroleum oil. The fractionatedcreosote oil residue was a particular fraction v of the residue boilingpoint range from 200 C. to 250 C. at 10 mm.

The table follows.

Coal tar fraction starting ma- Character of reac- Pour point vterialtion product lowering F.

Crude tower bottoms Heavy reddish- 5 brown free-flowing oil.Fractionated crude tower bot- Dark viscous 15 I ggggsraction B. P.- R.315- brown oil. Fractionated crude tower bot- Darkbrown grease 20 tomsfraction B. P. R. 330- 345 C. Alkali washed tower bottoms... Greenishbrown 15 viscous oil. Acid washed tower bottoms Light reddish- 5 browngrease. Acid washings from crude tower Brown waxy solid 20 bottoms.

Acid and alkali washed tower Dark red, waxy .5

bottoms. o Crude red wax Hariia dark red so 1 Crude red wax (70 parts)Soft red wax 35 Crude red wax (140 parts) Redldish brown 25 01 Acidwashed red wax Dark red wax- 5 Coaltaroverhead distillateB.P. Heavy darkred 35 R. 450-500 C. (70 parts). oil. Light coal tar bases Darigdredgreasy 10 S0 1 Heavy coal tar bases -.do 40' Heavy coal tar bases (70parts).. Dark brown soft waxy S Heavy coal tar bases (140 parts).Darfigrom waxy 10 so Crude anthracene...-..' Red 1waxy maene Crudeanthracene product pudo 35 rifled. Acid washed crude anthracene" Darkred oil .5 0212155216 distillate B. P. R. 300- Red free-flowing 10 0Coal tar distillate B. P. R. 300- Free flowing oil 5 375 C. (70 parts).Coal tar distillate B. P. R. 400- Red viscous 011.... 30 500 C. (70parts). Creosote oil residue (50 parts)... Brown viscous oil- 30Fractionated creosote oil residue vReddish brown oil 10 B. P. R. 200-250C. at 10 mm. (50 parts) Some .of the products we add to mineral oils arehighly colored and tend to discolor the oil. This is not ordinarilyobjectionable but we can obviate the disadvantage by treating theaddition products with a decolorizing agent such as" sources andobtained similar improvements. For

example, the addition of 5 percent of product made from crude red wax(70 parts) to a lubricating oil known as Atlantic red lowers the pourpoint of the oil 45 F. The addition of product made from the coal taroverhead distillate boiling point range 450-500 C. to Atlantic red showsa pour point lowering of F.

In appended claims we advantageously define the product which we add tolubricating oils as being the Friedel-Crafts reaction product from ahigher fatty acid chloride and a coal tar fraction. To those skilled inthe art this means a material made by reacting a higher fatty acidchloride with a coal tar fraction in the presence of aluminum chloride,hydrolizing the first reaction product containing aluminum, andisolating the final or Friedel-Crafts reaction product. We have alreadystated above what we mean by higher fatty acid chlorides. By coal tarfractions we mean those distillates obtained by distilling coal tar orby extracting coal tar with acids or bases.

Having thus described our invention, what we claim is:

l. A lubricating oil comprising a. mineral lubricating oil and a smallamount, of the order of 0.1 to 1 percent, of a Friedel-Crafts reactionproduct from a coal tar fraction and a fatty acid chloride having atleast six carbon atoms.

2. A lubricating oil comprising a mineral lubricating oil and a smallamount, of the order of 0.1 to 1 percent, of a Friedel-Crafts reactionproduct from a coal tar distillate and a fatty acid chloride having atleast six carbon atoms.

3. A lubricating oil comprising a mineral lubricating oil and a smallamount, of the order of 0.1 to 1 percent, of a. Friedel-Crafts reactionproduct from a coal tar fraction chosen from the group consisting ofalkali-soluble and acid-soluble portions of coal tar and a fatty acidchloride having at least six carbon atoms.

4. A lubricating oil comprising a mineral lubricating oil and a. smallamount, of the order of 0.1 to 1 percent, of a Friedel-Crafts reactionproduct from a fatty acid chloride having at least six carbon atoms andthe coal tar fraction red wax.

5. A lubricating oil comprising a mineral lubricating oil and a smallamount, of the order of 0.1 to 1 percent, of a Friedel-Crafts reactionproduct from heavy coal tar bases and a fatty acid chloride having atleast six carbon atoms.

6. A lubricating oil comprising a mineral lubricating oil and a smallamount, of the order of 0.1 to 1 percent, of a Friedel-Crafts reactionproduct from crude anthracene and a fatty acid chloride having at leastsix carbon atoms.

'7. A lubricating oil comprising a mineral lubricating oil and a smallamount, of the order of 0.1 to 1 percent, of a Friedel-Crafts reactionproduct from a coal tar fraction the major portion of which boils above200 C. and a fatty acid chloride having at least six carbon atoms.

8. A lubricating oil comprising a mineral lubricating oil and a smallamount, of the order of 0.1 to 1 percent, of a Friedel-Crafts reactionproduct from a fatty acid chloride having at least six carbon atoms anda coal tar distillate, the major portion of which boils above 200 C.

9. The oil as in claim 1 wherein the chloride is stearyl chloride.

10. The oil as in claim 2 wherein the chloride is stearyl chloride.

11. The oil as in claim 3 wherein the chloride is stearyl chloride.

12. The oil as in claim 4 wherein the chloride is stearyl chloride.

. 13. The oil as in claim 5 wherein the chloride is stearyl chloride.

14. The oil as in claim 6 wherein the chloride is stearyl chloride.

15. The oil as in claim 7 wherein the chloride is stearyl chloride.

16. The oil as in claim 8 wherein the chloride is stearyl chloride.

17. The process of improving lubricating oils which comprises adding asmall amount of a Friedel-Crafts reaction product from a coal tarfraction and a. fatty acid chloride having at least six carbon atoms, tothe oil.

ANDERSON W. RALSTON. CARL W. CHRISTENSEN. WILLIAM M. SELBY.

